After her husband is injured in a traffic accident and held responsible for it, housewife Ririko faces hospital bills, treatment costs and compensation payments. Drawn by an ad promising high pay and no experience required, she begins working part-time as a night guard after caring for him. Days after discussing reports of nearby robbers with a coworker, the inexperienced but diligent Ririko is suddenly assigned a shift alone—and hidden intruders turn the night into a nightmare...